1. Field of the Invention
The present invention relates a technology for touch panels, particularly to a time-reversal-based impact-localization and haptic-feedback method for touch panels.
2. Description of the Related Art
Touch panels may be categorized into the resistive type, the capacitive type, the sonic type, the optical type and the electromagnetic type. When a finger touches the sensor on a touch panel, the sensor sends out an analog signal. A controller converts the analog signal into a digital signal. The driver program of the computer integrates the related components to compile the digital signal. Then, the display card presents a screen signal on the screen to indicate the touched position.
There is a simpler but more precise technology to locate a touched position, called the TR (time-reversal signal processing) method. Firstly, the sensor array records the signal of each point (However, the signal may be affected by noise or reflected signals.) Next, time-reversal mirrors reverse the signal previously recorded to make the waveform automatically converge to the touched point. The TR method functions like a phase-conjugate filter. The TR method provides a delta function as the test signal and maximizes SNR (Signal Noise Ratio). In the conventional TR technology, the touch panel must be trained before it can trace back the touched position. In training a touch panel, the impulse response of each point must be recorded in the database. Further, when one intends to change the resolution of a touch panel, he has to spend time on measuring impulse responses and reconstructing the database.
Accordingly, the present invention proposes a time-reversal-based impact-localization and haptic-feedback method for touch panels to overcome the abovementioned problems. The principles and embodiments thereof are described in detail below.